It is known to do PCR or other forms of DNA amplification in a containment device, using, for example, a flexible pouch. Such is described in EPA 381,501, wherein flow of target and reagents proceeds past a detection chamber and into a dead-end waste compartment.
Although such a device is very effective, the use of a dead-end waste compartment can create on occasion a problem. That is, sufficient back-pressure from incoming flow can be created so as to interfere with the sequential reactions desired at the detection chamber. For example, back pressure tends to stress the detection chamber to the point that beads used to anchor the target can themselves become dislodged.
The most obvious solution to back-pressure caused by a dead-end waste compartment is to vent that compartment to the atmosphere. However, that is unacceptable since it defeats the first principle of PCR devices, namely that of keeping contained the amplified product.
Accordingly, prior to this invention it has not always been possible to ensure that no undesirable back- pressure will be created by a waste compartment such as might interfere with optimum results.